1. Field of the Invention
This invention relates to the field of the spectral analysis of a transmission path and particularly to a system in which the spectrum of signals received at a remote location is analyzed and displayed at a measuring location.
2. The Prior Art
In certain types of electronic signal transmission systems such as community antenna television (CATV) systems or cable transmission systems for transmitting television signals or other relatively side band signals, usually from a central location to a plurality of remote locations, it is important that the signals be transmitted in their entirety without the loss of signals in a part of the frequency band and certainly without the loss of all of the signals. Heretofore, the operators of such systems have had to depend upon routine maintenance or, usually, immediate complaint by system subscribers in the event of partial or total loss of signals at the subscriber's location. It is common for the transmission path between the central location and the subscriber's location to include a number of links and connections, and any part of the transmission path may include the point of signal loss. It is a time consuming procedure to trace out the signal passage along the transmission path to locate the point of loss. Such service is also costly, not only from the standpoint of the time of the people involved in the maintenance and their travel costs in reaching the maintenance locations, but frequently also in the costs of blocking traffic to reach a transmission cable in an underground conduit.
It is one of the principle objects of the present invention to measure transmission characteristics of a transmission path by scanning a relatively narrow band receiving means across the band of signals that should be received at a predetermined remote location, transforming the received signals into a signal that can be transmitted to a central location, and displaying the transformed signals to show the transmission characteristics of the transmission path as measured at the remote location.
Another object of the invention is to provide such analysis on an automatic basis.
A further object of the invention is to provide the analysis in sequence for a number of such remote locations.
Further objects will become apparent from the following specification together with the drawings.